Engine cleaner composition, method and apparatus with acetonitrile

ABSTRACT

An engine cleaner composition and method for removing carbonaceous deposits from engine fuel-system components such as mechanical and electronic fuel injectors, intake valve seats, valves, combustion cylinders, spark plugs, and oxygen sensors may be used on both gasoline and diesel engines. Preferred compositions comprise a synergistic solution of a heterocyclic ring compound in an azeotrope of acetonitrile and water, together with selected surfactants and aromatics. Preferred compositions of the invention may be placed in an aerosol pressurized unit utilizing a compressed gas, such as nitrogen or nitrous oxide, or compressed liquid gas, such as a hydrocarbon or fluorohydrocarbon. Preferred engine cleaning compositions of the invention are substantially non-ozone depleting, are low in global warming, and have a low order of human toxicity. Preferred compositions have a moderate pH and are essentially compatible with metals and elastomers conventionally used in engine fuel-system components. The invention provides a consumer or a professional engine mechanic with a safe, easy and efficient way to clean engine fuel-system components.

RELATED APPLICATION

This application is a continuation in part of our application, Ser. No.08/227,795, filed Apr. 14, 1994, now abandoned.

BACKGROUND ART

The efficient operation of a modern computer-controlledinternal-combustion engine depends in part on the ability of thecomputer of the engine to control accurately the air/fuel ratio and thetiming of the spark. Such accurate control requires that criticalcomponent parts of the system function at close to optimum O.E.M.values. One common hinderance to optimum operation has been the foulingof engine component parts with carbonaceous deposits.

Several years ago fouling of electronic fuel injectors in automobileengines became a serious problem. Injector cleaners were developed togive some relief to the injector fouling problem. After study of theproblem by O.E.M. engineers and oil company chemists, it was concludedthat possibly the most serious contributing factor to injector foulingwas the presence of high levels of diolefins, sulfides and other polarcompounds in gasolines. Other contributing factors included exhaust gasfrom exhaust-gas recirculation "EGR," positive crankcase ventilation("PCV") gas, positioning of injectors close to the intake valvesreceiving hot back-soak temperatures, and location of injector spraypintles close to the outer tips of the injectors.

In answer to the problem of fuel-injector fouling, certain manufacturersof electronic fuel injectors redesigned their injectors. In addition,certain O.E.M.'s repositioned their injectors further back from theintake valves. Oil companies significantly reduced diolefins, sulfides,and other polar compounds in gasoline, and, in addition, the companiesbegan to add alkylamine detergents to gasoline to help keep injectorsclean. As a consequence, fuel injector deposit problems have beenreduced significantly, although cleaning is occasionally still needed.However, deposits on other engine fuel areas remained a problem; e.g.intake valves, spark plugs, combustion chambers, and oxygen sensors.

With the passage of time, workers in the art were successful indeveloping several generic approaches for obviating the foregoinglimitations. Briefly, these techniques included the following.

(a) A carburetor cleansing operation which involves pouring a cleaningcomposition directly into an open air throttle on the carburetor withthe engine operating at a high rpm level. In this procedure, the cleaneremployed is admixed with the fuel and the combination burned during thecombustion process. As the cleaning liquid flows over the bottom of theintake runners in this operation, approximately 30% of the surfaces arecleaned.

(b) An injector cleaning process involving the use of a pressurizedcontainer having contained therein an engine fuel and a cleaning agentin a ratio of about four parts fuel to one part cleanser. Thepressurized container is connected to a transfer apparatus which is thenadapted to the injector fuel rail of the engine. The fuel system is thedisabled and the engine operated on the fuel/cleaner mixture from thepressurized container. This technique has been found to clean the fuelinjector satisfactorily but does not appear effect cleansing of theintake valves or valve seats.

(c) A vacuum disconnect technique which involves disconnecting a vacuumline on the air intake plenum and then connecting a rubber flex line tothe vacuum outlet. Following, the other end of the flex line is insertedinto a container of cleaning fluid. At that juncture, the engine isstarted and the vacuum used to evacuate the cleaning fluid from thecontainer into the plenum. The cleaning fluid then follows the route ofleast resistance to the center of gravity down the plenum from the pointof entry. Studies have revealed that some intake runners get the majorportion of the cleaning fluid while others get none. A furtherlimitation of this procedure arises in that the cleaning fluid does notcome into contact with the injectors and therefore provides limited orno cleaning.

(d) A commercial procedure to chemically clean mechanical and electronicfuel injectors together with upper engine components wherein chemicalcompositions are added to the fuel tank of a vehicle, cleansing beingeffected as the vehicle is operated. In the operation of such process itis common to employ 100 parts of fuel to one part of cleaning fluid.Studies of such processes have revealed that the use of high levels ofpolybuteneamine fuel additive result in the effective cleansing ofsoiled injectors. However, this has not proven effective at removinghardened carbonaceous deposits in the intake valve.

The numerous problems created by the presence of excessive carbonaceousdeposits on intake valves include engine power loss, accelerationproblems, higher emissions and fuel combustion, so creating a need forcorrection thereof. Currently, this end is effected either by removingthe intake valves, cleaning them and re-installing, or by removing theair intake manifold (plenum) and installing a "walnut shell blaster"which loosens the carbonaceous deposits using a high pressure force ofsmall walnut shell chips. Each of these procedures is labor intensiveand economically unattractive. Unless the vehicle in issue is stillunder warranty, the owner will generally wait until the vehicle failsemission tests or the engine operation deteriorates to the point whereit is malfunctioning.

Accordingly, it has been found that none of the aforementioned prior artprocedures has been able to provide the simultaneous cleansing of fuelsystem engine components such as air intake plenums, intake runners,intake valves and valve seats, oxygen sensors and catalytic converters.

U.S. Pat. No. 4,992,187 to Adams et al. disclosed a composition forcleaning an internal combustion engine which included a five-memberedheterocyclic ring compound and hydrazine. Although the composition ofthe patent could be effective in cleaning internal combustion engines,the composition had an undesirably high order of toxicity and wasexpensive. The technique of the patent generally required a skilledmechanical technician to clean the mechanical or electronic fuelinjectors of an engine and an especially high level of skill to cleanother upper engine fuel-system components.

U.S. Pat. No. 4,807,578 disclosed an injector cleaning system andtechnique. The technique required a quantity of an active injectorcleaner to be blended into a larger quantity of engine fuel. Theresulting blend was placed into a pressure resistant container and thenpressurized with a compressed gas, such as air or nitrogen. A specialadapter was used to attach the pressurized container to the fuel rail ofthe engine to be cleaned. In general, different engine models requireddifferent adapters. Consequently, a garage using the engine cleaningtechnique of the '578 patent had to stock a large number of adapters,with the number of adapters growing larger with each new vehicle model.

Although the injector cleaning system of the '578 patent can beeffective in cleaning fuel injectors, there are a number of drawbackswith this system in practice. For example, because the fuel/cleanermixture in the container is pressurized, several types of failure,although rare, present the hazard of a mechanic being sprayed with thecleaner/fuel or in the cleaner/fuel being sprayed onto a hot engine oronto painted surfaces of the vehicle, all with potentially seriousconsequences. Such potentially serious failures can arise if the threadsof the connector connecting the aerosol unit to the adapter apparatusare stripped by over tightening; or if a regulator diaphragm of theadapter apparatus ruptures; or if a fitting between the regulator and aball valve of the adapter apparatus breaks as a result of the stress ofopening and closing the ball valve over a period of time.

In addition, if the wrong adapter in the apparatus of the '578 patent isused to attach the pressurized container containing fuel and cleaner tothe fuel rail of the throttle body; or if the adapter seal leaks; or ifthe return fuel line plug is not sufficiently secured; of if the highpressure fuel line is not reattached to the fuel rail correctly, fuel orthe cleaner/fuel mixture can drip onto a hot engine.

Moreover, if the return fuel line is not clamped closed in the techniqueof the '578 patent, the injector cleaner can flow back to the fuel tank,which can result in damage to an electric fuel pump. If aninjector-cleaner apparatus of the patent remains attached to a fuel railovernight or over a weekend, damage can be caused to a diaphragm in thefuel-return pressure regulator.

Heretofore, the only solvents known to produce sufficient synergisticengine-cleaning activity for heterocyclic ring compounds were highlyalkaline compounds, such as alkylamines, ammonia, or hydrazine. Whensuch alkaline compounds are blended with certain heterocyclicfive-membered ring compounds, the resulting blend can be irritating tothe skin. As a result, use of such engine cleaners by the general publicis not recommended and even use by professionals is now beingquestioned.

A need exists for a safe and efficient chemical composition to cleaninjectors, intake valves, combustion chambers, spark plugs, oxygensensors and other fuel/combustion components of internal combustionengines which need not be injected into the high pressure side of thefuel-system fuel rail and for an engine cleaning process which is soinherently safe that persons with little or no mechanical skill canconduct the cleaning process.

It is an object of the invention to provide a composition of lowtoxicity capable of efficiently cleaning internal combustion engineparts which can be introduced into the engine through the air intakesystem. It is a further object of the invention to provide a method ofcleaning internal combustion engines which can be used safely byconsumers as well as skilled automobile mechanics and which isinexpensive relative to conventional engine-cleaning techniques.

It is yet a further object of the invention to provide an enginecleaning composition that has a moderate or neutral pH and which wouldprovide the cleaning power needed for the difficult job of cleaningcarbonaceous deposits from internal engine surfaces.

It is also an object of the present invention to provide an inexpensiveapparatus for cleaning injectors, air intake plenums, intake valves andvalve seats, combustion chambers, oxygen sensors and catalyticconverters, said apparatus having a cost less than that of a highquality screwdriver.

A still further object of the present invention is to provide a vehicleowner with a safe and simple technique coupled with a low cost apparatusthat has sufficient versatility to attach to the air intake plenum ofany internal combustion engine.

SUMMARY OF THE INVENTION

The invention broadly concerns the discovery that certain blends ofacetonitrile and water combined with certain heterocyclic ring compoundscan produce a synergistic cleaning effect for surfaces in internalcombustion engines subject to fouling.

The subject invention also provides an engine cleaner apparatus whichincludes a pressurized container which is charged with a quantity of apreferred cleaning composition of the invention or other suitablecleaning composition and a compressed liquid gas propellant, thecontainer being capable of adapting to the air intake plenum of aninternal combustion engine.

The subject invention provides an engine cleaner composition forremoving varnish and burned-on sludge from surfaces in an internalcombustion engine, which composition comprises (i) a ring-containingcompound wherein the ring compound includes one or more rings of five orsix consecutively linked atoms, and (ii) a blend of acetonitrile andwater. Preferably, the acetonitrile and water in the blend areessentially in proportions to form an azeotrope. Most preferably, therelative proportions of the ring compound and the blend of acetonitrileand water are such that the cleaning action of the ring compound and theblend of acetonitrile and water are synergistically significantlyincreased.

The engine cleaner composition of the invention comprises a heterocyclicring compound having a boiling point of about 250° F. or greater and ablend of X weight percent water and (100-X) weight percent acetonitrile,where X is in the range of from about 5 to about 25 weight percent basedon the combined weight of the water and the acetonitrile. Preferably, Xis in the range of from about 10 to about 20 weight percent based on thecombined weight of the water and the acetonitrile. Most preferably, X isapproximately equal to 16 weight percent so that the blend of water andacetonitrile are substantially in the proportions of awater/acetonitrile azeotrope.

Preferably, the engine cleaner composition of the invention includestwo, and more preferably three heterocyclic ring compounds.

Preferably, the engine-cleaner composition of the invention alsoincludes a surfactant. Preferably, the surfactant is isopropylaminedodecylbenzene sulfonate ("P-1059") or and polyoxylated alkyl phosphateester ("PS 222").

The engine-cleaner composition of the invention preferably also includesan aerosol propellant. Preferred aerosol propellants arefluorohydrocarbon "134-a" and an aerosol grade hydrocarbon blenddesignated in the trade "A-46."

An engine-cleaner method of the invention for cleaningcarbonaceous-deposits from internal surfaces of an internal combustionengine comprises the step of introducing a quantity of a preferredengine-cleaner composition of the invention or other suitableengine-cleaner composition into an air-intake manifold of the engine asan aerosol fog. The method of the invention also includes the step ofallowing the engine-cleaner composition to interact withcarbonaceous-deposit material on internal surfaces of the engine withthe engine off for an engine-cleaner-soak time sufficient to permit aportion of the engine-cleaner composition to soak into and loosen,soften, or dissolve carbonaceous-deposit material on the internalsurfaces. The engine cleaner method of the invention further includesthe step of running the engine for a time to remove carbonaceous-depositmaterial, loosened, softened, or dissolved by the engine cleaner frominternal surfaces of the engine.

Preferably, prior to the step of introducing the quantity ofengine-cleaner composition into the air-intake manifold of the engine,the engine is run for a time sufficient to warm up the engine.

Preferably, the method of the invention includes the step of adding aquantity of a surfactant fuel additive to the fuel of the engine.

Preferred engine-cleaner compositions of the invention have a low orderof toxicity, a moderate or neutral pH and are capable of efficientlyloosening, softening, dissolving and otherwise tending to removeepoxies, varnish and burned-on sludge in an internal combustion engine.Effective engine cleaning is provided with a synergistic mixture of oneor more carbonaceous-deposit-softening ring compounds having boilingpoints above typical engine operating temperatures of roughly 200°-220°F. and a water/acetonitrile ring-compound-cleaner activating solvent.

The following five heterocyclic ring compounds are preferred for theengine-cleaning compositions of the invention. Each of the fiveheterocyclic provides an advantageous combination of boiling pointtemperature vs. synergizable engine cleaning activity for dissolvingcarbonaceous engine deposits in the presence of a water/acetonitrileactivating solvent. ##STR1##

The heterocyclic ring compounds listed below tend to exhibit asynergistic increase in engine cleaning activity when combined with theazeotrope of water and acetonitrile and may be suitable to include in anengine cleaner composition for certain applications, although forreasons of toxicity, cost, boiling point, or incompatibility with othercomponents of the composition, they are generally less preferred thanthe preferred heterocyclic ring compounds listed above:

tetrahydrofuran

butyrolactone

N-ethyl-pyrrolidone

N-(2-hydroxyethyl)-2-pyrrolidone

N-(aminoethyl)-pyrrolidone

furfural

furan

tetrahydrofurfuryl alcohol

furfural alcohol

dibutyrolactam

N-butyl pyrrolidone

isopropyl pyrrolidone

isooctyl pyrrolidone

tetradecyl pyrrolidone

hexadecyl pyrrolidone

octadecyl pyrrolidone

octyl pyrrolidone

dodecyl pyrrolidone

cocalkyl pyrrolidone.

Other engine cleaner compositions which may be suitable in the enginecleaner process and engine cleaner apparatus of the invention in certainapplications include conventional gasoline-additive engine cleaners suchas the commercial gasoline-additive cleaners with the trade names"ORONITE OGA 273," available from Chevron Chemical Company of SanFrancisco, Calif.; "HITEC 4940," available from Ethyl PetroleumAdditives, Inc. of St. Louis, Mo., "Paradyne 741/PDN 2577," availablefrom Exxon Chemical Americas of Houston, Tex. and "LZ 8293," availablefrom The Lubrizol Corporation of Wickliffe, Ohio. Such commercialgasoline-additive cleaner compositions may be combined with an aerosolpropellant such as the propellant A-46 for use in the engine cleanermethod and engine cleaner apparatus of the invention. Preferredproportions are about 30 parts by weight gasoline-additive cleanercomposition and about 70 parts by weight aerosol propellant.

BRIEF DESCRIPTION OF THE FIGURES

Preferred embodiments of the invention are described below withreference to the following drawings:

FIG. 1 is a graph showing the cleaning efficiency of2-methyl-1,5-Bis(2-oxopyrrolidin-1-yl) pentane and an azeotrope blend ofacetonitrile and water on a spark plug with a category "a" soil ratingemersed for about 10 minutes at approximately 70° F.--a cleansingprocedure termed the "CSPIT" test. The dashed line represents anexpected theoretical curve. The solid line represents the actualexperimental curve, which exhibits a synergistic increase in cleaningefficiency.

FIG. 2 is a graph showing the cleaning efficiency ofN-cyclohexyl-2-pyrrolidone and the azeotrope of acetonitrile and waterusing the "CSPIT" cleaning procedure on a spark plug with a category "a"soil rating. The immersion time was about 10 minutes at approximately70° F. The dashed line represents the expected theoretical curve. Thesolid line represents the actual experimental curve, which exhibits asynergistic increase in cleaning efficiency.

FIG. 3 is a graph showing the cleaning efficiency of 2-furfurylamine andthe azeotrope of acetonitrile and water using the "CSPIT" cleaningprocedure on a spark plug with a soil rating of category "a" using anapproximately 10 minute immersion time at approximately 70° F. Thedashed line represents the expected theoretical curve. The solid linerepresents the actual experimental curve which exhibits a synergisticincrease in cleaning efficiency.

FIG. 4 is a graph showing the cleaning efficiency ofN-methyl-2-pyrrolidone and the azeotrope of acetonitrile and water usingthe "CSPIT" cleaning procedure on a soiled spark plug with a soil ratingof category "a" for about 10 minutes immersion time at approximately 70°F. The dashed line represents the expected theoretical curve and thesolid line represents the actual experimental curve which exhibits asynergistic increase in cleaning efficiency over a certain concentrationrange.

FIG. 5 is a graph showing the cleaning efficiency of 2-pyrrolidone andthe azeotrope of acetonitrile and water using the "CSPIT" cleaningprocedure on a soiled spark plug with a soil rating of category "a" forabout 10 minutes at approximately 70° F. The dashed line represents theexpected theoretical curve and the solid line represents the actualexperimental curve which exhibits a synergistic increase in cleaningefficiency.

FIG. 6 is a graph showing the cleaning efficiency of isopropylaminedodecylbenzene sulfonate and the azeotrope of acetonitrile and waterusing the "CSPIT" cleaning procedure on a soiled spark plug with a soilrating of category "a" for about 10 minutes at approximately 70° F. Thedashed and the solid lines are essentially the same. Essentially, nosynergism in cleaning efficiency was found.

FIG. 7 is a simplified perspective drawing of an automobile engineillustrating three preferred locations for introducing a preferredengine-cleaner composition of the invention into an air-intake plenum ofthe engine.

FIG. 8 is a side view of a preferred engine cleaner kit of the inventionfor dispensing an engine cleaner composition into an air-intake plenumof an internal combustion engine in the form of an aerosol fog.

FIG. 9 is an illustration of lower portions of nine automobile exhaustvalves soiled to varying degrees with carbonaceous deposits.

FIG. 10 is an oscilloscope trace of a signal from an oxygen sensor of anautomobile engine before cleaning.

FIG. 11 is an oscilloscope trace of a signal from the oxygen sensor ofthe automobile engine of FIG. 10 after cleaning by a preferred enginecleaner method of the invention.

FIG. 12 is a front elevational view of an aerosol actuator with aprotective plastic cover employed in the practice of the invention.

FIG. 13 is a cross-sectional view of a preferred male/three-diametermale uniform bore adapter employed in the practice of the invention.

FIG. 14 is a cross-sectional view of a preferred male/three-diametermale insert-holder adapter.

FIG. 15 is a cross sectional view of a preferred semi mechanicalbreak-up spray insert for use with the insert holder adapter of FIG. 14.

FIG. 16 is a cross-sectional view of a preferred male/three-diametermale dual-insert-holder adapter.

FIG. 17a is a side view of a Maltese cross post insert which can bepress fitted into the standard inside diameter channel of the plasticadapter of FIG. 16.

FIGS. 17b and 17c are cross-sectional views of the Maltese-cross insertof FIG. 17a taken along lines b-b' and c-c', respectively.

FIG. 18a is a cross-sectional side view of a swirl channel insert whichcan be press fitted into an insert holder socket of the plastic adapterof FIG. 16 downstream of the Maltese-cross insert of FIG. 17.

FIGS. 18b and 18c are cross-sectional views of the swirl channel insertof FIG. 18a taken along lines b-b' and c-c', respectively.

FIG. 19 is a side view, in perspective, of an aerosol unit employed inthe practice of the invention which has been fitted with an over capactuator with an adapter.

DETAILED DESCRIPTION OF THE INVENTION

N-cyclohexyl-2-pyrrolidone (CHP) was found to be responsive tosynergistic activity in engine cleaning effectiveness of the kinddiscussed in U.S. Pat. No. 4,992,187. The compound CHP was used tosearch for evidence of synergism in engine cleaning efficiency fromneutral pH solvents that were not identified as possible carcinogens byIARC, NTP, OSHA or ACGIH.

Surprisingly, the water azeotrope of acetonitrile was found to exhibitsynergistic activity with respect to CHP cleaning efficiency. Bothacetonitrile and water independently tested show essentially nosynergistic activity. Similar compounds such as dimethyl acetamide anddimethyl formamide show essentially no synergism either independently orcombined with water.

An appropriate theory to explain the observed synergistic increase incleaning efficiency is not available, especially synergistic increasesof the magnitude shown in FIG. 2.

Generally, more effective cleaning is obtained when soaking a fullywarmed-up engine, during a time the engine back-soak temperature rangesfrom about 250° F. to about 350° F. Immediately after a fully warmed-upengine is turned off, some of the engine surfaces to be cleaned, e.g.,the exhaust and intake valve seats, the spark plugs, the piston ringsand the oxygen sensor, are at temperatures around 750° F. and generallycool down rapidly to temperatures around 300° F. for from roughly 20 to30 minutes. Other engine surfaces to be cleaned, e.g., the intake valvetulips, the in-take valve stems, and the fuel injector tips are attemperatures around 200° F. immediately after a fully warmed-up engineis turned off and generally increase to temperatures around 300° F. inroughly 20 to roughly 30 minutes. The air throttle body is also cleaned,which generally has an average temperature around 150° F. immediatelyafter a fully warmed-up engine is turned off.

Engine hot-soak cleaning studies showed that generally the best cleaningresults were obtained using three synergized heterocyclic ringcompounds. Acceptable cleaning results were obtained using combinationsof two synergized heterocyclic ring compounds. When an engine cleanercomposition includes a combination of three ring compounds, at least twopreferably have boiling points of more than about 100° F. above theengine back-soak temperatures of approximately 300° F. When the enginecleaner composition includes only two heterocyclic ring compounds, theboiling point of one of the two is preferably about 200° F. above theengine back-soak temperature of approximately 300° F. The remainingheterocyclic ring compound in each case preferably has a boiling pointabout equal to the engine back-soak temperature of about 300° F.

If desired, the engine cleaner composition of the invention could beused to clean injectors and other engine parts in the manner of thecomposition described in U.S. Pat. No. 4,992,187, using an apparatus andadapters such as described in U.S. Pat. No. 4,807,578 to introduce thecomposition into the engine's high-pressure fuel-supply system. However,as noted above, the engine cleaning process of the '187 and '578 patentshas given rise to some problems even when used by professionals.

A preferred engine cleaning method of the invention is to charge apressure-resistant container of an aerosol engine cleaner kit with apreferred synergistic engine cleaner composition of the invention underpressure which includes an aerosol propellant liquid. Formula 61 fromTable III below is particularly preferred for this application. As shownin FIG. 8, an aerosol engine cleaner kit 2 has a flexhose 10 which canbe attached to an outlet fitting 8 of a push button valve 6 of apressure-resistant aerosol container 4. The push-button valve 6 permitsthe pressurized contents of the container 4 to be controllablydischarged through the flexhose 10. The flexhose 10 probably has aninside diameter of about 3/16 inch (4.8 mm) and a length of from aboutthree to about seven feet (1 to 2.1 m). The flexhose 10 may be made ofneoprene, Buna rubber, natural rubber, polyethylene orpolyvinylchloride, for example. The aerosol engine cleaner kit alsoincludes a male/dual-diameter flexhose coupler 12, a greater diametercoupling hose 16 and a lesser diameter coupling hose 17.

The greater diameter coupling hose 16 preferably has an inside diameterof about 1/2 inch (12.7 mm) and the lesser diameter coupling hose 17preferably has an inside diameter of about 3/8 inch (9.5 mm). Thecoupling hoses 16 and 17 are each preferably from two to three inches(51 to 76 mm) long. The male/dual-diameter male flexhose coupler 12 isgenerally tubular in construction with a bore passing substantiallyaxially through it. The coupler 12 has a barbed inlet fitting 13 adaptedto be inserted into and snugly held by a discharge end of the flexhose10. The male/dual-diameter male coupler 12 also has a lesser diameterbarbed outlet fitting 14 at an end opposite to the inlet fitting 13. Thelesser-diameter outlet fitting 14 is adapted to be inserted into andsnugly held by an inlet end of the lesser diameter coupling hose 17. Asshown in FIG. 8, intermediate between the inlet fitting 13 and thelesser diameter outlet fitting 14 on the male/dual-diameter male coupler12 is a greater-diameter barbed outlet fitting 15. The greater-diameteroutlet fitting 15 is adapted to be inserted into and snugly held by aninlet end of the greater-diameter coupling hose 16, with thelesser-diameter outlet fitting 14 extending into the hose of thegreater-diameter coupling hose 16.

The male/dual-diameter male flexhose coupler 12 together with thegreater and lesser diameter coupling hoses 16 and 17 permit flexhose 10to be coupled to standard-sized ports of the air-intake manifold ofconventional internal combustion engines. As may be seen in FIG. 7, aconventional internal combustion engine 100 has an air-intake-plenumhousing 102 which encloses an air-intake plenum (not shown). A positivecrankcase ventilation ("PVC") hose 104 extends from a PVC valve 106which communicates with an internal crankcase chamber of the engine to aPVC intake port fitting 108 which provides communication with theair-intake plenum through the air-take-plenum housing 102. Thepositive-crankcase-ventilation hose 104 conventionally has an insidediameter of about 3/8 inch (9.5 mm). To connect the flexhose 10 of theaerosol engine-cleaner kit 2 to the engine 100 for discharge of enginecleaner composition as an aerosol fog into the air-intake plenum of theengine, the positive-crankcase-ventilation hose 104 can be disconnectedfrom the PVC intake port fitting 108 and the discharge end of theflexhose 10 connected to the PVC intake port fitting 108 by means of themale/dual-diameter male flexhose coupler 12 and the lesser-diametercoupling hose 17. As an alternative connection arrangement which may bemore convenient in certain vehicles, the positive-crankhose-ventilationhose 104 can be left connected to the PVC intake port fitting 108 anddisconnected from the PVC valve 106. The discharge end of the flexhose10 can then be connected to the positive-crankcase-ventilation hose 104by means of the male/dual-diameter male flexhose coupler 12.

A third alternative for connecting the flexhose 10 of the aerosolengine-cleaner kit 2 to the engine 100 for discharge of engine cleanercomposition as an aerosol fog into the air-intake plenum of the engineinvolves a brake vacuum line 110 which extends from a brake-vacuum-lineport fitting 112 in the air-intake plenum housing 102 to an air vacuumbrake canister 114. In many vehicles, the brake vacuum line 110 has aninside diameter of either about 3/8 inch (9.5 mm) or about 1/2 inch(12.7 mm). To connect the flexhose 10 of the aerosol engine-cleaner kit2 to the engine 100 for discharge of engine cleaner composition as anaerosol fog into the air intake plenum of the engine, the brake vacuumline 110 can be disconnected from the brake-vacuum-line port fitting 112and the discharge end of the flexhose 10 connected to thebrake-vacuum-line port fitting 112 by means of the male/dual-diametermale flexhose coupler 12 and the coupling hose 16 or 17 of the diametercorresponding to the diameter of the brake vacuum line 110.

The three to seven foot length of the flexhose 10 permits a personcleaning the engine to sit in the driver's seat of the vehicle for thecleaning operation. In a preferred embodiment of the present invention acold concentrate chemical fog is transferred from the air intake plenumthrough the catalytic converter.

One particularly preferred engine-cleaning method for an automobileengine involves placing the gearshift of the automobile in park, thenstarting the engine and accelerating the engine to an engine speed ofabout 2500 RPM using the gas pedal. The push-button valve of the aerosolunit is then pressed to introduce engine cleaner composition into theair-throttle body of the engine. When engine speed starts to drop, thepush-button valve of the aerosol unit is released. The press and releaseoperation of the valve of the aerosol unit is repeated about four timesin one minute; then the push-button valve is held down continuouslyuntil the engine stalls. The accelerator pedal is then released. Theengine is then cranked with the starter motor for about 10 seconds, withthe push-button valve of the aerosol unit fully depressed. The vehiclekey is then switched off. The push-button valve is then depressed untilthe aerosol container unit empties, which is generally within one minuteafter the cranking is stopped. The engine is then allowed to "soak" forfrom about 10 to about 30 minutes. While the engine is soaking, theflexhose or the 3/8" barbed male probe is removed and the PCV linereconnected to the air throttle body or air intake plenum. A gasolineadditive is then added to the fuel tank. When the soak period is over,the engine is started and brought to a speed of approximately 2500 RPMand held until all blue smoke leaves the exhaust, which generally takestwo minutes or so.

Alternatively, the pressure-resistant container can be pressurized witha compressed gas such as carbon dioxide (CO₂), nitrous oxide (NO₂) ornitrogen (N₂). See Table III below, Formula Nos. 56, 57, 58 and 59. Theaerosol unit is connected to the air throttle body and the enginecleaning process is carried out in essentially the same manner asoutlined in the preceding paragraphs.

Although it is not recommended that any embodiment of the engine cleanercomposition of the invention be ingested or inhaled in highconcentrations, preferred engine cleaner compositions of the inventionexhibit a low toxicity when used in accordance with the preferred enginecleaner method of the invention. When an engine is being cleaned by theengine cleaner method of the invention, exhaust gases from the enginewhen it is running or being cranked should be vented out-of-doors inaccordance with standard, safe garage-operation practice for handlingautomobile-engine exhaust. Running an engine after soaking with apreferred engine cleaner composition of the invention can lead to anincrease in the concentration of nitrous oxide (NO₂) in the exhaustrelative to the concentration under conditions of ordinary operation ofthe engine.

Best and Preferred Modes for Carrying out The Invention

Test methods for determining product cleaning efficacy have beendeveloped. Such methods have been used to obtain data on the relativecleaning efficiency of individual chemicals and of combinations of twoor three or four chemicals that may show synergistic activity, or oncompletely formulated concentrates. The following screeningmethod--termed the "cold spark-plug immersion test" ("CSPIT")--was foundto be useful in predicting the efficiency of a test cleaning agent forcleaning surfaces of internal combustion engines subject to fouling:

a. Carefully remove a soiled spark plug from an engine;

b. Using an air knife, blow away any loose contamination and note thevisual appearance of spark plug;

c. Weigh the soiled spark plug;

d. Immerse the soiled spark plug in the test liquid for about 10 minutesat approximately 70° F.;

e. Remove the spark plug from the test liquid and rinse it momentarilywith water at ambient temperature;

f. Air dry or blow gently with an air knife until dry;

g. Re-weigh the spark plug and note the weight loss due to soil removal;

h. Note the visual appearance of the dry spark plug after immersion inthe test liquid and estimate the approximate percent of soil removalbased on the original appearance of the soiled spark plug;

i. Visually inspect the test solution and estimate the percent of soildissolved from the discoloration of the solution;

j. Using a mild abrasive buffing wheel or an ultrasonic cleaning bath,remove all soil left on the spark plug, if any;

k. Re-weigh the cleaned spark plug and note the weight loss; and

l. Calculate percent soil removal due to immersion in the test liquidfrom the weighings in steps c, g, and k and estimate the percent soilremoval from the visual inspections in steps b, h, and i.

If the three estimations of percent soil removal closely agree, thenrecord the percent soil removal. If they do not agree, repeat the testwith another soiled spark plug.

In the cold spark plug immersion test, it is necessary to separatesoiled spark plugs into three categories:

a) heavy, baked-on varnish/sludge deposits;

b) light, baked-on varnish/sludge deposits;

c) highly carbonized, baked-on varnish/sludge deposits.

The tests described below were conducted on category "a" type plugsunless indicated otherwise.

In addition to the CSPIT screening tests, cleaning effectiveness testshave been made on automotive engines. Such tests--termed "hot enginecleaning tests" ("HECT")--are based on determination of such attributesas:

a) Cleaning of oxygen sensors: measured by observing signal patternsfrom the sensors with the oscilloscope of a pinpoint tester before andafter cleaning;

b) Conducting a cylinder power balance test before and after cleaning;

c) Dynamic firing voltages (kV), measured before and after cleaning;

d) Firing duration, measured before and after cleaning;

e) Exhaust gas emissions, analyzed before and after cleaning;

f) Pinpoint test of injector pulse width, measured before and aftercleaning; and

g) Minimum smooth idling speed, measured before and after cleaning.

Test engine cleaner compositions that rate 50 percent soil removal orbetter from the cold spark-plug immersion test "CSPIT" test when testedin an engine were generally found to produce excellent results in thehot engine cleaning tests "a" through "g." In the case of preferredengine cleaner formulas of the subject invention, "CSPIT" removal ofabout 50 percent or greater is considered to be desirable, and removalof about 75 percent or greater is considered to be exceptionally good.

Tables I, II and III below set forth the results of "CSPIT" testscarried out on spark plugs with a category "a" soil rating using varioustest compounds and multicomponent test compositions. The percentagesnoted for the components of the multicomponent test compositions referto weight percentages based on the total weight of the composition.

                  TABLE I    ______________________________________                            % of Soil Removal                            Using "CSPIT"                            Test For About                            10 Minutes and                            a Spark Plug With    Test Compounds          Soil Rating "a"    ______________________________________    1.  2-methyl-1,5-Bis(2-oxopyrrolidin-1-yl)pentane                                10         "ACS 2002"!    2.  N-cyclohexyl-2-pyrrolidone  "CHP"!                                20    3.  2-furfurylamine         40    4.  N-methyl-2-pyrrolidone  40    5.  2-pyrrolidone           30    6.  isopropylamine dodecylbenzene sulfonate                                3        (CAS No. 26264-05-1)  "P-1059"!    7.  polyoxyalkylated alkyl phosphate ester                                1        (CAS No. 68071-35-2)  "PS 222"!    8.  azeotrope of acetonitrile and water                                0    9.  deionized water         0    10. toluene                 0    ______________________________________

                  TABLE II    ______________________________________    Multi Component             "CSPIT"    Test Compositions           Test    ______________________________________    11. 2-methyl-1,5-Bis(2-oxopyrrolidin-1-yl)pentane                                75%     20        azeotrope of acetonitrile and water                                25%    12. 2-methyl-1,5-Bis(2-oxopyrrolidin-1-yl)pentane                                50%     40        azeotrope of acetonitrile and water                                50%    13. 2-methyl-1,5-Bis(2-oxopyrrolidin-1-yl)pentane                                25%     50        azeotrope of acetonitrile and water                                75%    14. N-cyclohexyl-2-pyrrolidone                                75%     70        azeotrope of acetonitrile and water                                25%    15. N-cyclohexyl-2-pyrrolidone                                50%     60        azeotrope of acetonitrile and water                                50%    16. N-cyclohexyl-2-pyrrolidone                                25%     30        azeotrope of acetonitrile and water                                75%    17. 2-furfurlyamine         75%     80        azeotrope of acetonitrile and water                                25%    18. 2-furfurlyamine         50%     80        azeotrope of acetonitrile and water                                50%    19. 2-furfurlyamine         25%     50        azeotrope of acetonitrile and water                                75%    20. N-methyl-2-pyrrolidone  75%     50        azeotrope of acetonitrile and water                                25%    21. N-methyl-2-pyrrolidone  50%     50        azeotrope of acetonitrile and water                                50%    22. N-methyl-2-pyrrolidone  25%     40        azeotrope of acetonitrile and water                                75%    23. 2-pyrrolidone           75%     60        azeotrope of acetonitrile and water                                25%    24. 2-pyrrolidone           50%     50        azeotrope of acetonitrile and water                                50%    25. 2-pyrrolidone           25%     40        azeotrope of acetonitrile and water                                75%    26. isoproplyamine dodecylbezene sulfonate                                75%     2        azeotrope of acetonitrile and water                                25%    27. isoproplyamine dodecylbezene sulfonate                                50%     0        azeotrope of acetonitrile and water                                50%    28. isoproplyamine dodecylbezene sulfonate                                25%     0        azeotrope of acetonitrile and water                                75%    29. N-cyclohexyl-2-pyrrolidone                                33.3%   80        2-furfuryzamine         33.3%        azeotrope of acetonitrile and water                                33.3%    30. ACS 2002                33.3%   70        CHP                     33.3%        azeotrope of acetonitrile and water                                33.3%    31. CHP                     33.3%   70        N-methyl-2-pyrrolidone  33.3%        azeotrope of acetonitrile and water                                33.3%    32. CHP                     33.3%   65        2-pyrrolidone           33.3%        azeotrope of acetonitrile and water                                33.3%    33. ACS 2002                33.3%   75        2-furfurylamine         33.3%        azeotrope of acetonitrile and water                                33.3%    34. 2-furfurylamine         33.3%   85        N-methyl-2-pyrrolidone  33.3%        azeotrope of acetonitrile and water                                33.3%    35. ACS 2002                33.3%   65        N-methyl-2-pyrrolidone  33.3%        azeotrope of acetonitrile and water                                33.3%    36. 2-furfurylamine         33.3%   80        2-pyrrolidone           33.3%        azeotrope of acetonitrile and water                                33.3%    37. CHP                     30.0%   80        2-furfurlamine          30.0%        azeotrope of acetonitrile and water                                30.0%        isopropylamine dodecylbenzene sulphonate                                10.0%    38  ACS 2002                30.0%   75        2-furfurlamine          30.0%        azeotrope of acetonitrile and water                                30.0%        P-1059                  10.0%    39. ACS 2002                30.0%   60        CHP                     30.0%        azeotrope of acetonitrile and water                                30.0%        P-1059                  10.0%    40. CHP                     26.6%   80        2-furfurylamine         26.7%        azeotrope of acetonitrile and water                                26.7%        P-1059                  20.0%    41. CHP                     26.6%   80        2-furfurylamine         23.3%        azeotrope of acetonitrile and water                                23.4%        P-1059                  30.0%    42. CHP                     20.0%   75        2-furfurylamine         20.0%        azeotrope of acetonitrile and water                                20.0%        P-1059                  40.0%    43. CHP                     16.6%   60        2-furfurylamine         16.6%        azeotrope of acetonitrile and water                                16.8%        P-1059                  50.0%    44. ACS 2002                16.6%   60        2-furfurylamine         16.6%        azeotrope of acetonitrile and water                                16.8%        P-1059                  50.0%    45. ACS 2002                25.0%   80        2-furfurylamine         25.0%        azeotrope of acetonitrile and water                                25.0%        P-1059                  20.0%        PS222                   5.0%    46. CHP                     25.0%   80        2-furfurylamine         25.0%        azeotrope of acetonitrile and water                                25.0%        P-1059                  20.0%        PS222                   5.0%    47. ACS 2002                15.0%   80        2-furfurylamine         30.0%        azeotrope of acetonitrile and water                                20.0%        P-1059                  30.0%        PS222                   5.0%    48. CHP                     30.0%   75        2-furfurylamine         15.0%        azeotrope of acetonitrile and water                                20.0%        P-1059                  30.0%        PS222                   5.0%    49. CHP                     30.0%   75        2-furfurylamine         20.0%        azeotrope of acetonitrile and water                                20.0%        P-1059                  20.0%        PS. 222                 5.0%        diethylamine            5.0%    ______________________________________

                  TABLE III    ______________________________________                              "CSPIT"    Composition               Test    ______________________________________    50.  CHP                  7.50%   65         2-furfurylamine      5.70%         azeotrope of acetonitrile and water                              6.80%         P-1059               5.00%         PS222                0.85%         toluene              29.15%         A-46 propellant      45.00%    51.  ACS 2002             4.0%    50         2-furfurylamine      5.0%         azeotrope of acetonitrile and water                              5.0%         P-1059               8.0%         PS222                3.0%         toluene              30.0%         A-46 propellant      45.0%    52.  ACS 2002             3.0%    75         CHP                  6.0%         2-furfurylamine      9.0%         azeotrope of acetonitrile and water                              5.0%         P-1059               6.0%         PS222                1.0%         toluene              30.0%         A-46 propellant      40.0%    53.  ACS 2002             4.0%    75         CHP                  3.0%         2-furfurylamine      10.0%         azeotrope of acetonitrile and water                              7.0%         P-1059               8.0%         PS222                3.0%         toluene              25.0%         A-46 propellant      40.0%    54.  ACS 2002             50.0%   75         CHP                  3.0%         2-furfurylamine      10.0%         azeotrope of acetonitrile and water                              7.0%         P-1059               8.0%         PS222                3.0%         toluene              34.0%         fluorohydrocarbon "134-a" propellant                              30.0%    55.  ACS 2002             3.0%    70         2-pyrrolidone        7.0%         2-furfurylamine      8.0%         azeotrope of acetonitrile and water                              7.0%         P-1059               8.0%         PS222                3.0%         toluene              34.0%         fluorohydrocarbon "134-a" propellant                              30.0%    56.  ACS 2002             4.0%    75         N-methyl-2-pyrrolidone                              10.0%         CHP                  8.0%         azeotrope of acetonitrile and water                              8.0%         P-1059               8.0%         PS222                3.0%         ethanol or methanol  56.0%         nitrous oxide (N.sub.2 O)                              3.0%    57.  ACS 2002             4.0%    85         N-methyl-2-pyrrolidone                              10.0%         2-pyrrolidone        8.0%         azeotrope of acetonitrile and water                              8.0%         P-1059               8.0%         PS222                4.0%         toluene              30.0%         isopentane or hexane or heptane                              25.0%         nitrous oxide (N.sub.2 O)                              3.0%    58.  ACS 2002             4.0%    80         N-methyl-2-pyrrolidone                              10.0%         2-pyrrolidone        8.0%         azeotrope of acetonitrile and water                              8.0%         P-1059               8.0%         PS222                3.0%         ethanol or methanol  30.0%         isopropyl alcohol    25.0%         carbon dioxide (CO.sub.2)                              4.0%    59.  ACS 2002             4.0%    85         N-methyl-2-pyrrolidone                              10.0%         2-pyrrolidone        8.0%         azeotrope of acetonitrile and water                              8.0%         P-1059               8.0%         PS222                3.0%         toluene              23.7%         isopentane           35.0%         nitrogen (N.sub.2)   0.3%    60.  N-methyl-2-pyrrolidone                              10.0%   85         CHP                  6.0%         2-furfurylamine      6.0%         azeotrope of acetonitrile and water                              8.0%         toluene              20.00%         dimethyl ether (D.M.E.)                              50.00%    61.  N-methyl-2-pyrrolidone                              10.71%  90         CHP                  5.36%         2-furfurylamine      5.36%         azeotrope of acetonitrile and water                              8.57%         A-46 propellant      20.00%         dimethyl ether (D.M.E.)                              50.00%    ______________________________________

Because of the solvent ability of dimethyl ether, surfactants are notused in formulas Nos. 60 and 61. In formula 56, methanol is generallypreferred for reasons of economy. In formula 57 isopentane is the morevolatile than hexane or heptane and so is generally preferred.

In order to clean effectively engine fuel system components subject tofouling by carbonaceous deposits--e.g. the intake air throttle body, thefuel injectors, the intake valves, the combustion chambers, the sparkplugs, exhaust valves, the oxygen sensor and the catalyticconverter--using a cleaning composition introduced into the air intakesystem, compressed liquid gas provides an ideal vehicle. Formulas Nos.50 through 59 contain surfactants--isopropyalmine dodecylbenzenesulfonate and polyoxyalkylated alkyl phosphate ester--at concentrationseffective to solubilize the cyclic compounds into the compressed liquidpropellants.

When an engine-cleaner composition and propellant is sprayed from anaerosol unit into the air-intake system of a warmed-up internalcombustion engine, the stream of liquid rapidly expands, since theliquid stream is in a pressure environment of substantially oneatmosphere and in an intake manifold that generally averages above 130°F. The rapid expansion of the liquid propellant to a gas micronizes theengine-cleaner composition actives into droplets of which most are lessthan roughly one micron size. In the case of preferred engine-cleanercompositions of the invention, a dense cloud of fog of synergisticheterocyclic ring compounds and acetonitrile/water azeotrope is thuscreated. This dense active fog is carried throughout all areas of theupper engine system.

The small particle chemical fog having an average liquid particle sizeless than 0.1 micron obtained in the practice of the present inventionis used as the mechanism for providing the cleansing of engine parts. Inthe operation of the process, the pressure of the aerosol propellanttogether with the vacuum created by spinning the engine using thevehicle's starter pulls the fog through all areas of the air intakeplenum, the plenum runners wetting each intake valve and the valvehousing and all areas of the combustion chambers and spark plugs. Then,the chemical fog is pushed out and in so doing wets the exhaust valves,the oxygen sensor and the catalytic converter. Studies have shown thatthe deposits which dirty the fuel injectors start at the outside tip ofthe injector and plates back up to the pintlet needle, such depositsinterfering with the injector fuel spray pattern and the fuel volume. Asthe micro chemical fog wets the injector tips and the surfaces aroundthe pintlet needle it removes oil deposits and returns the fuelcharacteristics to o.e.m. specifications.

In order to obtain a small particle chemical fog, it is generallynecessary to use greater than 50% , by volume, liquid propellant andover 70% is a preferred level. Additionally, creation of a swirlingaction in the liquid spray using a mechanical break-up adapter shown inFIGS. 14 and 16 with fog-generating inserts shown in FIGS. 15, 17, and18 is a preferred embodiment of the present invention. The swirlingliquid spray super cools as it expands into a fog. It has beendetermined that when the cool fog first wets the hot soiled engine fuelsystem component surfaces, a network of small cracks occur on thesurface of the soil, so permitting the cleaning channels to penetratethe soil more rapidly. Instant cracking and pulling of the soil ofttimesoccurs on some of the valve intake housings. As the fog droplets warm,the propellant tends to fractionate from the cleaning fluid, therebyleaving the chemical droplets in a concentrated form. High boilingchemicals in the composition tend to precipitate against all surfaceslike a fog impinging upon a cold mirror.

With reference now to FIG. 12, there is shown a side elevational view ofan aerosol actuator used in the practice of a preferred embodiment ofthe present invention. Shown is an aerosol actuator valve 21 adapted tobe connected to an outlet of a pressure-resistant aerosol container 20.The aerosol actuator valve 21 has a protective plastic cover 22 which isconnected to a thick walled translucent plastic discharge tube 23 bymeans of a plastic lock sleeve 24. The discharge tube 23 has in outsidediameter of about 5/16 inch (7.9 mm) and an inside diameter of about3/16 inch (4.8 mm). The discharge tube 23 is about three feet (900 mm)long.

Turning now to FIG. 13, a male/triple-diameter male uniform-bore adapter25 has a barbed inlet fitting 29 which fits into the discharge tube 23of FIG. 12. The discharge tube 23 is locked on to the inlet fitting 29of the adapter 25 by means of lock sleeve 34. An air-intake plenum sideof adapter 25 is designed to fit into the bores of flexhoses of threedifferent diameters that are standard components of air intake plenumsof conventional vehicles. A small-diameter barbed tip 26 of the adapter25 fits into a hose with an inner diameter of approximately 3/16 inch(4.8 mm), medium-diameter barbed tip 27 fits into a hose with an innerdiameter of approximately 3/8 inch (9.5 mm), and a large-diameter barbedtip 28 fits into a hose with an inner diameter of approximately 1/2 inch(12.7 mm). The uniform-bore adapter 25 has a bore 35 which extendsaxially through the adapter. The bore 35 has an essentially a uniformdiameter of about 0.1 inch (2.5 mm) throughout. Dischargingengine-cleaner composition through the bore 35 of themale/triple-diameter male straight-through adapter 25 tends to producenon-mechanical break-up spray characteristics.

FIG. 14 is a cross-sectional view of a male/triple-diameter maleinsert-holder adapter 36. The insert-holder adapter 36 of FIG. 14 issimilar in structure to the uniform-bore adapter 25 shown in FIG. 13with the exception that a bore 30 passing axially through theinsert-holder adapter 36 is enlarged in diameter at an exit end to forman insert-holder socket 31. Turning now to FIG. 15, a semi-mechanicalbreak-up spray insert 50 is shown in an expanded scale relative to thescale of the insert-holder adapter 36 of FIG. 14. The semi-mechanicalbreak-up spray insert 50 is generally cylindrically symmetric inconstruction with a break-up spray bore 52 extending axially through theinsert. An insert plug fitting 54 projects from an inlet end of thebreak-up spray insert 50. The insert plug fitting 54 is shaped anddimensioned to be inserted in the insert-holder socket 31 of theinsert-holder adapter 36 and held in the socket 31 by a press-fitmechanism. An outlet end of the break-up spray bore 52 is shaped to forma semi-mechanical break-up spray orifice 56. An inlet end 58 of thebreak-up spray bore 52 is approximately 0.076 inch (1.9 mm) in diameter.At the outlet end, a radially inwardly projecting annular strip 60constricts the bore 52 to a diameter of about 0.056 inch (1.4 mm) on anupstream side, which increases generally linearly in a downstreamdirection to a diameter of about 0.060 inch (1.5 mm). The projectingstrip is about 0.022 inch (0.6 mm) wide in an axial direction. Thediameter of the bore 52 increases downstream of the projecting strip 60to a diameter of about 0.067 inch (1.7 mm) for a length of about 0.034inch (0.9 mm). A generally annular groove 62 encircles thesemi-mechanical break-up spray orifice 56 to receive and hold an end ofa flexhose. In operation, liquid back pressure exerted on the differentsized exit openings produces a semi-mechanical break-up spray ofengine-cleaner composition passing through the semi-mechanical break-upspray orifice 56 to form an aerosol fog of the composition.

Turning now to FIG. 16, a male/triple-diameter male dual-insert-holderadapter 38 is generally similar in construction to the uniform-boreadapter 25 of FIG. 13 with the exception that a small diameter fitting72 at the outlet end is not barbed in the dual-insert-holder adapter 38and a bore 39 which extends axially through the dual-insert-holderadapter 38 is enlarged in diameter at an outlet end to define adual-insert-holder socket 70. Turning now to FIG. 17a, a Maltese-crossupstream insert 76 is shown for clarity in an expanded scale relative tothe dual-insert-holder adapter 38 of FIG. 16. The upstream insert 76 hasa Maltese-cross plug fitting 78 which projects from an upstream-insertbody member 80. The plug fitting 78 has a Maltese-cross shape in crosssection, as may be seen FIG. 17b. As shown in FIG. 17a and 17c, theupstream-insert body member 80 is generally circularly cylindrical inshape. The Maltese-cross upstream-insert 76 is shaped and dimensioned tobe inserted in and held in the dual-insert-holder socket 70 of thedual-insert-holder adapter 38, with the Maltese-cross plug fitting 78projecting into an outlet end portion 74 of the bore 39 of the adapter38. The upstream-insert 76 is held in place by radially inner walls ofthe outlet end portion 74 of the bore 39 bearing against radially outersurfaces of the arms of the Maltese-Cross-shaped plug fitting 78 in apress-fit relationship. The outer diameter of the upstream-insert bodymember 80 is less than the inner diameter of the dual-insert holdersocket 70, so that when the Maltese-cross upstream insert 76 ispositioned in the bore of the adapter, an annular channel is definedbetween radially-outer surfaces of the body member 80 and radially innersurfaces of the holder socket 70. Four axially extending grooves 84 aredefined along the Maltese-cross plug fitting 78 by the cross-shapedcross section of the fitting. Each of the four axially extending grooves84 is connected to a corresponding generally radial groove 82 formed inan upstream base of the upstream-insert body member 80, as shown in FIG.17a. The axially-extending grooves 84, the radial grooves 82 and theannular channel (not shown) between radially outer surfaces of theupstream insert body member 80 and radially inner surfaces of the holdersocket 70 permit fluid to flow from the inlet end of the bore 39 of theadapter 38 into the holder socket 70.

Turning now to FIG. 18a, a downstream swirl-flow cap insert is shown inan expanded scale relative to the dual insert holder adapter 38 of FIG.16. The downstream cap insert 86 is generally circular in cross section,as may be seen in FIGS. 18b and 18c. The downstream cap insert 86 isdimensioned to be inserted in and held by the holder socket 70 of thedual insert holder adapter 38 in a press-fit arrangement downstream ofthe upstream insert 78. An interior cavity of the insert 86 is shaped todefine a swirl chamber 88. The downstream cap insert 86 is oriented inthe holder socket 70 of the adapter 38 with an inlet opening 94 of theswirl chamber 88 facing upstream towards the Maltese-cross upstreaminsert 78. Radial-offset grooves 90 are formed in an upstream-facingdownstream face of the swirl chamber 88 of the cap insert 86, as may beseen best in FIG. 18b. The grooves 90 are about 0.01 inch (0.3 mm) deepby about 0.01 inch (0.3 mm) wide. A stepped diameter orifice 92 providesa fluid outlet from the interior of the swirl chamber 88. The steppeddiameter orifice 92 has an upstream diameter of about 0.06 inch (1.5 mm)and a downstream exit diameter of about 0.04 inch (1 mm).

The Maltese-cross upstream insert 76 and the swirl chamber downstreamcap insert 86 when mounted in the dual insert adapter 38 cooperate inoperation to produce a full mechanical break up of engine-cleanercomposition flowing through the bore 39 of the adapter to generate anaerosol fog of the composition.

FIG. 19 is a side view, in perspective of an aerosol unit 51 fitted withan over cap actuator 55 having an adapter 53 of the invention attachedthereto.

A preferred process for cleaning internal combustion engines is asfollows:

1. Fully warm the engine of interest.

2. Disconnect the electrical harness leading to all of the fuelinjectors.

3. Disconnect a rubber vacuum line that connects to the air intakeplenum.

4. Connect a small two inch (2") piece of rubber hose to the exposedprobe on the plenum shown in FIG. 20.

5. Connect the three stage adapter to this small rubber hose as shown inFIG. 19.

6. Fully actuate the aerosol unit and spray for 3-4 seconds. Then, usingthe vehicle's starter, spin the engine for 10 seconds while fullyactuating the spray.

7. Stop the cranking but continue to spray for 3 seconds at which timespraying is stopped.

8. The hot engine is the permitted to soak for a time period within therange of 10-20 minutes.

9. Steps 6, 7 and 8 are then repeated.

10. Disconnect the adapter, remove the small rubber hose and reconnectthe vacuum line.

11. Reconnect the electrical harness leading to the fuel, injectors.

12. Press the gas pedal to the floor and start the engine, holding therpm at about 2,500 for two minutes or until the exhaust smokedisappears. At that point, the accelerator is snapped to 4,000 rpm a fewtimes making sure all loose carbon is blown out the exhaust. At thatpoint, the engine fuel component systems are clean.

This cleaning procedure should be repeated once or twice a year or every12,000 to 15,000 miles to keep the engine clean and operating at maximumefficiency while maintaining emission at minimum levels.

FIG. 8 shows preferred hoses and adapters for introducing one preferredengine-cleaner composition of the invention into the air-throttle bodyof an automotive engine. Preferably, the hose has an internal diameterof about 3/16 inch or less, which tends to prevent the propellant fromexpanding and supercooling the product at the exit of the actuator.Supercooling in the hose tends to cause a spray of larger particles andliquid, which tends to cause hot spots and prevents complete enginesaturation and optimum engine cleaning.

Engine cleaning hot-soak studies were conducted on fully warmed-upengines to determine an engine cleaning time required to returnengine-fuel system components to O.E.M. specifications. The soak timesin the engine cleaning process were compared to the "CSPIT" test resultsobtained with the same engine-cleaning composition. Formula No. 51 had arating of about 50 percent on the "CSPIT" procedure and requiredapproximately 30 minutes soak time to clean engine fuel-systemcomponents to O.E.M. specifications. Formula No. 50 had a rating of 65percent from the "CSPIT" procedure and required approximately 20 minutessoak time to clean engine fuel-system components to O.E.M.specifications. Formulas Nos. 52, 53, 54, 55 and 56 had ratings of fromabout 70 to about 75 percent from the "CSPIT" procedure and requiredfrom 15 to approximately 20 minutes soak time to clean enginefuel-system components to O.E.M. specifications. Formulas Nos. 57, 58and 59 had ratings of from about 80 to 85 percent from the "CSPIT"procedure and required from about 10 to about 15 minutes soak time toclean engine fuel-system components to O.E.M. specifications.

Boroscope examination of upper engine surfaces before and aftertreatment with a preferred engine cleaner of the invention byapproximately one-minute pulse spraying with the cleaner with the enginerunning at approximately 2500 RPM shows the areas that were covered withthin layers of carbonaceous deposits and varnish were effectivelycleaned. Boroscope examination after saturating substantially all areaswith the active fog and hot soaking from about 10 to about 30 minutesshows that the higher boiling ring compounds condense on substantiallyall internal surface areas, slowly turning the carbonaceous deposits toa black running liquid. This liquid is either washed off by gasolinewhen the engine is restarted or is blown off by the hot violent gasmovement when the engine is running at an engine speed of approximately2000 RPM. When there is heavy coking on the intake valve tulip pad, thehigh-boiling synergistic ring compounds soak into the spongy cokedeposits, loosening, softening and dissolving the coke.

Removal of the coke deposits may be facilitated by the use of a gasolineadditive. The preferred additive for this purpose is 2-furfurylamine ata concentration of from about 25 to about 30 grams in approximatelyfifteen gallons of gasoline. A trade gasoline additive commerciallyavailable from Exxon Chemical Co. under the trade name "Paradyn 741" isalso effective for facilitating the cleaning action of the ringcompounds at a concentration of from 50 to about 60 grams per 15 gallonsof gasoline. Alkylamine surfactants in the gasoline additives helpgasoline to wash off the softened spongy coke residue that remains onthe valve tulip pad after hot soaking.

FIG. 10 shows the electrical response of an oxygen sensor in asix-cylinder, 4.9-liter electronic fuel injection engine before theengine was soaked for about 10 minutes with Formula No. 61. The vehiclepowered by the engine had an odometer mileage of around 83,000 miles.FIG. 11 shows the electrical response after cleaning this engine.Comparison of FIGS. 10 and 11 will show that the cleaning resulted in asignificant improvement in the electrical response of the oxygen sensor.

Table IV below shows the cylinder power balance on the six-cylinder,4.9-liter electronic fuel injection engine of FIG. 10 before cleaningwith Formula No. 61. Table V below shows the test results aftercleaning.

A fuel-metering pulse width from the electronic fuel injector for theengine before cleaning was measured and found to stay open forapproximately 7.18 milliseconds. The fuel on this same six cylinderengine was flowing through all injectors for approximately 7.18milliseconds per each opening. The number of openings per minute staysconstant. The engine idling speed 15 for this recording was about 709rpm. After cleaning, measurement showed the fuel-metering pulse width tobe approximately 6.27 milliseconds per opening. The engine-controlcomputer adjusted the air/fuel ratios and restricted the fuel-meteringpulse width by approximately 12 percent because of the higher fuel flowrate after cleaning. The engine idling speed for the measurement aftercleaning was approximately 725 RPM.

Table VI shows electrical data for the six cylinder engine. The widespread of the kV firing voltage before cleaning indicates dirty sparkplugs. Table VII shows the engine electrical data after cleaning. Thelower kV and more consistent firing voltage between spark plugs rangeindicates cleaner spark plugs.

Table VIII shows the kV duration before cleaning. Note the durationrange is lower and the duration spread between the spark plugs isgreater. A longer spark duration range gives a more complete air/fuelcylinder burn, maximum power and minimum harmful emissions. The durationconsistency of kV between cylinders contributes to a more equal powerbalance between cylinders and smoother engine running.

Table IX shows the desired kV duration is over 6 percent longer aftercleaning and the kV range between cylinders is tighter.

The engines were retested after driving approximately 300 miles with arecommended gasoline additive. Only minor improvements were observed onall electronic tests. Cylinder compression improved, cold engine startsimproved and cold engine driveability improved. The most notableimprovements were observed on removal of carbonaceous deposits on intakevalves. The two gasoline additives, 2-furfurylamine and "Paradyne 741",were tested for carbonaceous deposit removal from intake valves withoutthe synergistic engine cleaner soaking technique. The average removalafter driving 300 miles was 200 to 500 mg. See FIG. 9 for baroscopecarbonaceous deposit rating on intake valves.

Value class No. 1 is ˜0.2 gms of deposits

Value class No. 2 is ˜0.5 gms of deposits

Value class No. 3 is ˜1.0 gms of deposits

Value class No. 4 is ˜2.0 gms. of deposits

Value class No. 5 is ˜4-5 gms of deposits

Value class No. 6 is ˜6-7 gms of deposits

Value class No. 7 is ˜8-10 gms of deposits

Value class No. 8 is ˜11-13 gms. of deposits

Value class No. 9 is ˜14 gms. of deposits

The average deposit removal from intake valves for approximately 10minutes soaking with the preferred synergistic formulas of the inventioncan be from about 3 to about 4 grams. The average deposit removal forapproximately 20 minutes soaking can be from about 4 to about 5 grams.Tests also show that after driving 300 miles using either gasolineadditive after soaking, the deposit removal quantity can be roughlyequal to the removal obtained during the soak. This example representsthe general boroscope observation. A boroscope rating of No. 6 beforesoaking a fully warmed up engine generally shows the same intake valueto be a rating of No. 4 after the 20 minute approximately soak cleaningprocedure, and a rating of No. 1 after driving approximately 300 mileswith the gasoline additive. A boroscope rating of No. 7 before soakingcan show the same intake value to be a No. 5 rating after theapproximately 20 minute soak cleaning procedure, and a No. 2 to 3 ratingafter then driving about 300 miles with the gasoline additive. Ahoroscope rating of a No. 7 before soaking generally can measure about10 mm thick carbonaceous deposit. A preferred synergistic engine cleanercomposition of the invention can soak into the porous coke deposit toaround 10 mm depth in about 20 minutes at an engine back soaktemperature of from about 250° F. to about 300° F. Approximately 2 mm ofthe coke can be dissolved in the approximately 20 minute soak cycle.Approximately another 3 mm can become very soft and wash off during theapproximately two minute engine running cycle at the end of theapproximately 20 minute soak period. Another approximately 4 to 5 mm ofdeposit can gradually be removed during the next approximately 300 miledriving with the gasoline additive. However, the approximately 5 mm ofcoke deposits left after the cleaning cycle can gradually harden andremain on the intake valve if the proper gasoline additive is not used.

                  TABLE IV    ______________________________________    SHORTING POWER BALANCE BEFORE CLEANING                   RPM      HC    CYL            CHANGE   CHANGE    ______________________________________    1              -16      230    5              -20       20+    3              -28      300    6              -40      120    2               -5      340    4              -43      680    MIN            -14      170    MAD            -63      880    BASE           610       0    ______________________________________

                  TABLE V    ______________________________________    SHORTING POWER BALANCE AFTER CLEANING                   RPM      HC    CYL            CHANGE   CHANGE    ______________________________________    1               3       1960    5              -26      2030    3               -4      1990    6               -3      2080    2               -7      2070    4              -24      2110    MIN             -1      1440    MAD            -46      2310    BASE           710       199    ______________________________________

                  TABLE VI    ______________________________________    ENGINE DATA BEFORE CLEANING    ______________________________________    IDLE TEST               MIN          RESULTS  MAX    ______________________________________    RPM        650          709      750    DWELL DEG  9.00         23.3     39.6    VOLTS      13.6         13.9     14.6    AMPS       1            ****     25    RIPPLE     0.00         0.00     0.12    COIL       0.10         0.82     1.50    VAC H.sub.2 O               197.1        275.6    339.9    TEMP °F.               145          202      239    HC         0            0        300    CO         0.00         0.15     3.00    O.sup.2    0.00         0.00     2.50    CO.sup.2   10.0         7.05     --    A/F RATIO  --           14.6     --    LAMBDA     --           0.983    --    ______________________________________    RPM 833   PEAK RPM    3341      COIL OSC 3    CYL       LOW         RESULTS   HIGH    ______________________________________    kV FIRING    1         8.6         9.8       12.0    5         6.4         7.5       8.7    3         8.0         9.3       10.9    6         5.6         8.8       10.7    2         6.1         9.8       11.1    4         6.4         8.3       9.1    MIN LIMIT 7.8         MAX LIMIT 10.8    kV SPARK    1         1.32        1.38      1.49    5         1.34        1.49      1.64    3         1.22        1.33      1.49    6         1.27        1.46      1.59    2         1.37        1.49      1.66    4         1.44        1.56      1.79    MIN LIMIT 1.25        MAX LIMIT 1.77    ______________________________________

                  TABLE VII    ______________________________________    ENGINE DATA AFTER CLEANING    ______________________________________    IDLE TEST               MIN          RESULTS  MAX    ______________________________________    RPM        650          725      750    DWELL DEG  9.00         23.4     39.6    VOLTS      13.6         13.8     14.6    AMPS       1            0        25    RIPPLE     0.00         0.00     0.12    COIL       0.10         0.80     1.50    VAC "H.sub.2 O               197.1        278.4    339.9    TEMP °F.               145          197      239    HC         0            0        300    CO         0.00         0.19     3.00    O.sup.2    0.00         0.39     2.50    CO.sup.2   10.0         6.79     --    A/F RATIO  --           15.1     --    LAMBDA     --           1.018    --    ______________________________________    RPM 951   PEAK RPM    3567      COIL OSC 3    CYL       LOW         RESULTS   HIGH    ______________________________________    kV FIRING    1         5.2         5.8       6.6    5         4.8         5.8       6.4    3         4.9         5.7       6.5    6         4.7         5.9       7.0    2         5.5         6.3       7.0    4         6.0         6.8       7.6    MIN LIMIT 5.0         MAX LIMIT 8.0    kV SPARK    1         1.37        1.43      1.56    5         1.34        1.51      1.71    3         1.27        1.45      1.61    6         1.39        1.49      1.59    2         1.37        1.47      1.61    4         1.37        1.49      1.54    MIN LIMIT 1.26        MAX LIMIT 1.76    ______________________________________

It is not intended to limit the present invention to the specificembodiments and formulations described above. It is recognized thatchanges may be made in the formulations, steps and embodiments describedherein without departing from the scope and teachings of the instantinvention, and it is intended to encompass all other embodiments,alternatives and modifications consistent with the subject invention.

What is claimed is:
 1. An engine cleaner composition comprising(a) aheterocyclic ring compound having a boiling point of about 250° F. orgreater; (b) wherein said the heterocyclic ring compound is selectedfrom the group consistingof:2-methyl-1,5-Bis(2-oxopyrrolidin-1-yl)pentane,N-cyclohexyl-2-pyrrolidone,2-furfurylamine,N-methyl-2-pyrrolidone, and2-pyrrolidone; and (c) a blend of X weightpercent water and (100-X) weight percent acetonitrile, where X is in therange of from about 5 to about 25 weight percent based on the combinedweight of the water and the acetonitrile.
 2. The engine cleanercomposition according to claim 1 further comprising a secondheterocyclic ring compound, the second heterocyclic ring compound havinga boiling point of about 500° F. or greater.
 3. The engine cleanercomposition according to claim 2 in which X is in the range of fromabout 10 to about 20 weight percent based on the combined weight of thewater and the acetonitrile.
 4. The engine cleaner composition accordingto claim 3 in which the blend of water and acetonitrile aresubstantially in the proportions of a water/acetonitrile azeotrope. 5.An engine cleaner apparatus attachable to an air-intake system of aninternal combustion engine for introducing an engine cleaner compositioninto an air-intake plenum of the air-intake system in the form of anaerosol fog, the engine cleaner apparatus comprising:(a) apressure-resistant container having a discharge outlet, the containerbeing charged with an engine cleaner composition; (b) amanually-actuatable valve connected to the discharge outlet of thepressure-resistant container; (c) a flexhose having an inlet end and anoutlet end with a flexhose bore extending through the flexhose from theinlet end to the outlet end, the inlet end being connected to themanually-actuatable valve for receiving engine cleaner compositiondischarged from the pressure-resistant container upon actuation of thevalve; and (d) an air-intake-system adapter fitting connected to theoutlet end of the flexhose, the adapter fitting being shaped anddimensioned to be connected to an air-intake-system element to providecommunication between the bore of the flexhose and the air-intake plenumof the air intake system for introducing an aerosol fog of enginecleaner into the air-intake plenum; and (e) wherein the engine cleanercomposition comprises:(i) a heterocyclic ring compound having a boilingpoint of about 250° F. or greater, (ii) a blend of X weight percentwater and (100-X) weight percent acetonitrile, where X is in the rangeof from about 5 to about 25 weight percent based on the combined weightof the water and the acetonitrile, and (iii) an aerosol propellant. 6.The engine-cleaner composition according to claim 2 further comprising asurfactant other than the hetrocyclic ring compounds.
 7. Theengine-cleaner composition according to claim 6 in which the surfactantis selected from the group consisting of isopropylamine dodecylbenzenesulfonate and polyoxylated alkyl phosphate ester.
 8. The engine-cleanercomposition according to claim 1 further comprising an aerosolpropellant.
 9. The engine cleaning composition of claim 8 wherein theaerosol propellant is present in an amount greater than 50%, by volumeand has a boiling point less than 32° F.
 10. The engine cleaningcomposition of claim 9 wherein the aerosol propellant is present in anamount of more than 70%, by volume.
 11. The engine cleaner compositionaccording to claim 8 in which the aerosol propellant is afluorohydrocarbon.
 12. An engine cleaner composition comprising:(a)three heterocyclic ring compounds, a first and a second of the threeheterocyclic ring compounds having a boiling point of about 400° F. orgreater and a third of the heterocyclic ring compounds having a boilingpoint in the range of from about 250° F. to about 400° F.; (b) whereinsaid first, second and third of the heterocyclic ring compounds areselected from the group consistingof:2-methyl-1,5-Bis(2-oxopyrrolidin-1-yl)pentane,N-cyclohexyl-2-pyrrolidone,2-furfurylamine,N-methyl-2-pyrrolidone, and2-pyrrolidone and; (c) a blend of X weightpercent water and (100-X) weight percent acetonitrile, where X is in therange of from about 5 to about 25 weight percent based on the combinedweight of the water and the acetonitrile.
 13. The engine cleanercomposition according to claim 12 in which X is in the range of fromabout 10 to about 20 weight percent based on the combined weight of thewater and the acetonitrile.
 14. The engine cleaner composition accordingto claim 13 in which the blend of water and acetonitrile aresubstantially in the proportions of 84 wt % acetonitrile and 16 wt %water.
 15. The engine cleaner apparatus according to claim 5 in whichthe air-intake-system adapter fitting includes a coupler adapter and aswirl-chamber cap insert, the coupler adapter having a bore extendinggenerally axially through the adapter, an outlet end of the bore beingshaped and dimensioned to receive and retain the swirl-chamber cap, theswirl-chamber cap being shaped to define a swirl chamber within aninterior of the cap, interior surfaces of the swirl-chamber cap facingthe swirl chamber having swirl-flow-inducing elements formed therein, anoutlet orifice passing through the swirl-chamber cap to permit fluid toflow out of the swirl chamber through the orifice, theswirl-flow-inducing elements formed in the interior surfaces of theswirl-chamber cap being effective to induce a swirling flow of fluidpassing through the swirl chamber, the coupler adapter and swirl chambercap being effective to tend to form a full mechanical break up spray inoperation when an engine-cleaner composition is passed through the bore.16. The engine-cleaner composition according to claim 12 furthercomprising a surfactant.
 17. The engine-cleaner composition according toclaim 16 in which the surfactant is selected from the group consistingof isopropylamine dodecylbenzene sulfonate and polyoxyalkylated alkylphosphate ester.
 18. The engine-cleaner composition according to claim12 further comprising an aerosol propellant.
 19. The engine cleanercomposition according to claim 18 in which the aerosol propellant isselected from the group consisting of propane, isobutane, normal butane,fluorohydrocarbon "134-a" and an aerosol grade hydrocarbon blenddesignated in the trade "A-46" or "A-60", fluorocarbon "152a", dimethylether and mixtures thereof.
 20. An engine-cleaner method for cleaningcarbonaceous-deposits from internal surfaces of an internal combustionengine comprising the steps of:(a) generating an aerosol fog of anengine-cleaner composition comprised of:(i) a heterocyclic ring compoundhaving a boiling point of about 250° F. or greater; and (ii) a blend ofX weight percent water and (100-X) weight percent acetonitrile, where Xis in the range of from about 5 to about 25 weight percent based on thecombined weight of the water and the acetonitrile; (b) introducing aquantity of the aerosol fog into an air-intake manifold of the engine;(c) allowing the engine-cleaner composition to interact withcarbonaceous-deposit material on internal surfaces of the engine withthe engine off for an engine-cleaner-soak time sufficient to permit aportion of the engine-cleaner composition to soak into and loosen,soften or dissolve carbonaceous-deposit material on the internalsurface; and (d) running the engine for a time to removecarbonaceous-deposit material, loosened, softened or dissolved by theengine cleaner from internal surfaces of the engine.
 21. The enginecleaner method according to claim 20 further comprising the step of:prior to the step (b) of introducing the quantity of aerosol fog ofengine-cleaner composition into the air-intake manifold of the engine,running the engine for a time sufficient to warm up the engine.
 22. Theengine cleaner method according to claim 21 further comprising the stepof adding a quantity of a surfactant fuel additive to the fuel of theengine.
 23. The engine cleaner apparatus according to claim 15 in whichthe air-intake-system adapter fitting further includes a Maltese-Crossinsert positioned within the bore of the coupler adapter upstream of theswirl-chamber cap.
 24. The engine cleaner method according to claim 20in which the blend of water and acetonitrile of the engine cleanercomposition are substantially in the proportions of a water/acetonitrileazeotrope.
 25. The engine cleaner method according to claim 24 in whichthe engine cleaner composition comprises three heterocyclic ringcompounds, a first and a second of the three heterocyclic ring compoundshaving a boiling point of about 400° F. or greater and a third of theheterocyclic ring compounds having a boiling point in the range of fromabout 250° F. to about 400° F.
 26. The engine cleaner method accordingto claim 25 in which each of the first, the second and the third of theheterocyclic ring compounds of the composition are selected from thegroup consisting of:2-methyl-1,5-Bis(2-oxopyrrolidin-1-yl)pentane,N-cyclohexyl-2-pyrrolidone, 2-furfurylamine, N-methyl-2-pyrrolidone, and2-pyrrolidone.
 27. The engine cleaner method according to claim 26 inwhich the engine cleaner composition further comprises a surfactant. 28.The engine cleaner apparatus of claim 5 in which the engine cleanercomposition comprises:(i) three heterocyclic ring compounds, a first anda second of the three heterocyclic ring compounds having a boiling pointof about 400° F. or greater and a third of the heterocyclic ringcompounds having a boiling point in the range of from about 250° F. toabout 400° F.; (ii) a blend of X weight percent water and (100-X) weightpercent acetonitrile, where X is in the range of from about 5 to about25 weight percent based on the combined weight of the water and theacetonitrile, and (iii) an aerosol propellant.
 29. The air cleanerapparatus of claim 5 in which the air-intake-system adapter fittingincludes a coupler flexhose and a male/male coupler adapter, saidcoupler adapter being shaped and dimensioned to be connected to anoutlet end of the flexhose, said coupler flexhose being connectable atone end to an end of the coupler adapter, the coupler flexhose alsobeing connectable at an opposing end to an air-intake-systemporta-fitting element of the engine providing communication with theair-intake plenum.
 30. The engine cleaner apparatus of claim 29 in whichthe air-intake-system adapter fitting includes a male/plural-diametermale coupler adapter having a bore extending generally axiallytherethrough from an inlet end to an outlet end, an outlet side of theadapter being shaped to form a series of generally cylindricaloutlet-side coupler elements of differing outside diameters, the outsidediameters of the outlet-side coupler elements decreasing in a step-wisefashion along the adapter in a direction advancing from the inlet endtowards the outlet end.
 31. The engine cleaner apparatus of claim 30wherein the male/plural-diameter male coupler adapter includesoutlet-side coupler elements dimensioned to fit within and retain flexhoses of three different inside diameters, a smaller outlet-side couplerelement dimensioned for a 3/16" inside diameter hose, an intermediateoutlet-side coupler element being dimensioned for a 3/8" inside diameterhose and a larger outlet-side coupler element being dimensioned for a1/2" inside diameter hose.
 32. The engine cleaner apparatus of claim 30in which each coupler element has barbed outer surface portions forretaining a hose fitted around the coupler element.
 33. The enginecleaner apparatus according to claim 5 in which the air-intake-systemadapter fitting includes a coupler adapter having a bore extendinggenerally axially through the adapter, the bore having a substantiallyuniform inside diameter along the length of the bore, the diameter ofthe bore of the coupler adapter being effective to tend to form anonmechanical break-up spray in operation when an engine-cleanercomposition including an aerosol propellant is passed through the bore.34. The engine cleaner apparatus according to claim 33 in which thediameter of the bore of the coupler adapter is about 0.1 inch (2.5 mm).35. The engine cleaner apparatus according to claim 5 in which theair-intake-system adapter fitting includes a coupler adapter having abore extending generally through the adapter, the bore havingconstriction in diameter in an axial location proximate to an outlet endof the bore, the constriction being effective to tend to form asemi-mechanical break-up spray in operation when an engine-cleanercomposition including an aerosol propellant is passed through the bore.36. The engine cleaner apparatus according to claim 34 in which each ofthe first, the second and the third of the heterocyclic ring compoundsof the composition are selected from the group consistingof:2-methyl-1,5-Bis(2-oxopyrrolidin-1-yl)pentane,N-cyclohexyl-2-pyrrolidone, 2-furfurylamine, N-methyl-2-pyrrolidone, and2-pyrrolidone.
 37. The engine-cleaner apparatus according to claim 36 inwhich the engine cleaner composition further comprises a surfactant.